Method of temporarily securing a die to a burn-in carrier

ABSTRACT

A method of using adhesive tape to temporarily retain a die being temporarily held in a fixture during testing and burn-in. The method of the present invention uses a die cut piece of adhesively coated tape to hold a die in a test and burn-in fixture. Upon subsequent heating of the tape beyond the normal operating range of the adhesive coating on the tape, the die is removed from the tape, the tape is removed from the test and burn-in fixture, and the remaining adhesive, if any, is removed from the test and burn-in fixture.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method of temporarily securing a die to aburn-in carrier for the purpose of burn-in and testing of the die. Morespecifically, this invention relates to a method of temporarily securinga die to a burn-in carrier through the use of adhesive tape for thepurpose of burn-in and testing of the die.

2. State of the Art

Integrated circuit memory devices, such as dynamic random accessmemories (DRAMS) and static random access memories (SRAMS) are testedduring manufacture and often prior to use. Such testing is for thepurpose of insuring that only known good dies are subsequently used.

One of the test procedures which is used to determine the viability ofintegrated semiconductor circuits is a burn-in procedure. The burn-intest is intended to stress the electrical interconnection of the die anddrive any contaminants in the body of the die into the active circuitry,thus causing failure. This test is based on data that indicated diesthat are prone to these types of failures will actually malfunction inthe early part of their lifetime. By conducting burn-in tests, the earlyfailures of the dies are detected and only known good dies aresubsequently used in applications.

In the testing of dies prior to encapsulation, temporary electricalconnection must be effected between the die and a test fixture. This istypically done by connecting the test fixture to the die using the bondpads of the die through the use of wire bonds or tape automated bonding.As is evident, the testing of an unpackaged or bare die requires asignificant amount of handling. Since the test package must be separatedfrom the die, the temporary packaging may be more complicated thaneither standard discrete packaging or multichip module packaging. Thepackage must be compatible with any desired test and burn-in procedureswithout damaging the die at the bond pads or elsewhere during any suchtest or burn-in procedure.

In U.S. Pat. No. 4,899,107, a reusable burn-in test fixture for discretetape automated bonding (TAB) dies is disclosed. The fixture consists oftwo halves, one of which is a die cavity plate for receivingsemiconductor dies as the units under test and the other halfestablishes electrical contact with the dice and with the burn-in oven.The dice are held in position within the carrier by being resilientlymounted therein.

In U.S. Pat. No. 5,408,190, a reusable burn-in test fixture for discretedice is disclosed. The reusable burn-in test fixture comprises twohalves, the first half containing a cavity in which a die is inserted.As disclosed, a precured RTV silicone backing strip is used to retain adie in a face-up position in the carrier. The precured RTV strip,commonly known as a “gel pack,” exhibits a static charge sufficient andcoefficient of friction sufficient to hold an intermediate substrate inplace without the use of adhesive and elastomerically biases the dieagainst the cover plate of the test fixture.

In U.S. Pat. No. 5,336,649, a precured RTV silicone strip, “gel pack,”is used for temporarily securing the die in place within a package body.The RTV silicone strip exhibits a static charge sufficient andcoefficient of friction sufficient to hold the die in place within aburn-in carrier. Another embodiment discloses the use of a tape type dieattach adhesive, known under the trademark of E. I. duPont de Nemours ofWilmington, Del. as “Kapton QL Die Attach Adhesive”, to hold the die inplace during burn-in. The adhesive is heated, but for a shorter timethan for a permanently packaged die. This allows a standard processsetup to be used for temporary die attachment while permitting theadhesive attachment of the die to be readily overcome subsequent totesting and burn-in. Also disclosed is the use of water soluble hot meltglass, a thermoplastic material, to temporarily hold the die duringtesting and burn-in. After testing, the hot melt glass is removed bydissolving it using deionized water, thereby freeing the die from thepackage. In yet another instance, the die may be adhesively bonded tothe carrier through the use of a sugar and water solution. Aftertesting, the package including the die is placed in deionized water,which causes the sugar to dissolve, thereby freeing the die from thepackage.

However, these prior types of die attachment techniques have inherentproblems. They either require specific types of mechanical mountingarrangements to be designed into the burn-in carrier, or require thatthe silicone “gel pack” exhibit sufficient electrostatic change toretain the die in the burn-in carrier, or require the careful sprayingof the adhesive in the burn-in carrier to minimize overspray of theadhesive, or require the use of a water cleaning solution after testingand burn-in to remove the adhesive remnants.

SUMMARY OF THE INVENTION

The present invention is directed to a method of using adhesive tape totemporarily retain a die being temporarily held in a fixture duringtesting and burn-in. The method of the present invention uses a die cutpiece of adhesively coated tape to hold a die inma test and burn-infixture. Upon subsequent heating of the tape beyond the normal operatingrange of the adhesive coating on the tape, the die is removed from thetape, the tape is removed from the test and burn-in fixture, and theremaining adhesive, if any, is removed from the test and burn-infixture.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood when the drawings aretaken in conjunction with the description of the invention wherein:

FIG. 1 is a top view of a substrate on which a softbond wirebondconnection has been made during the method of the present invention;

FIG. 2 is a partial cross sectional view of the substrate shown indrawing FIG. 1;

FIG. 3 is a flow diagram of the present invention; and

FIG. 4 is a sectional view of the die cutting the adhesively coated tapeof the present invention and the vacuum transfer apparatus which may beused in the present invention.

DESCRIPTION OF THE INVENTION

Referring to drawing FIGS. 1 and 2, a testing and burn-in fixture 10includes a package body 12 and a cover plate 14. The package body 12includes a die receiving cavity 16 in which a die 2 is retained. The diereceiving cavity 16 has any desired size and shape which is necessary toaccommodate the die 2 to act as a carrier for the testing and burn-in ofthe die 2. A plurality of external connector leads 18 extend from thetesting and burn-in fixture 10 to connect the die 2 to external testingand burn-in circuitry. In this instance, the external connectors 18 areattached to the package body, extend therefrom, and are shown asconnector pins 18, which are used in a dual in-line package or quad flatpack configuration. The external connectors 18 terminate in contact pads20 in the package body 12 which are generally in line with the bond pads22 of the die 2. The bond pads 22 of the die 2 are connected to thecontact pads 20 of the package body 12 by lead wires 24 to allow testingof the die 2.

Referring to drawing FIG. 2, the testing and burn-in fixture 10 is shownin a partial cross sectional view. As shown, the testing and burn-infixture may include one or more holes 26 located in the bottom of thepackage body 12 to use in the removal of the die 2 therefrom. Alsoshown, a piece of adhesively coated tape 30 is located between the die 2and the bottom of the package body 12 to retain the die 2 during thetesting and burn-in of the die 2.

Any suitable type of high temperature, pressure sensitive, adhesivelycoated tape 30 may be used to retain the die 2 in the package body 12during the testing and burn-in thereof. The adhesively coated tape 30may be coated with adhesive on either a single side or on both sides, asdesired. The tape 30 is cut to such size and shape as is necessary tofit within the package body 12 to retain the die 2 therein duringtesting and burn-in. It is not necessary that the adhesive tape 30 becut to the size of the die 2 being held in the fixture 10 during testingand burn-in thereof. While any suitable high temperature, pressuresensitive adhesive tape 30 may be used, it is preferred that the tape 30have an adhesive thereon with a maximum working temperature ofapproximately 180 degrees Centigrade. Also, the tape 30 may usediffering types of suitable adhesives thereon, such as pressuresensitive silicone adhesive, acrylic adhesive, etc. It is also desirablefor the adhesive on the tape 30 to leave a non-conductive ash when itoxidizes or burns to prevent any potential problems of electricalconnections with any portion of any die 2 being tested or duringburn-in. In situations where the die 2 does not need to be tested orsubject to burn-in temperatures of up to and including approximately 180degrees Centigrade and a lower testing and burn-in temperature isacceptable, an adhesive such as an acrylic adhesive which is suitable upto approximately 155 degrees Centigrade may be used. Also, for ease ofprocessing, it is desirable that tape 30 be backed tape, such as throughthe use of paper or the like so that the piece of the tape 30 to be usedin the fixture 10 may be easily, readily cut by a suitable cutting diehaving the desired configuration without the cutting die cutting throughthe paper backing on the tape. In this manner, the piece of tape 30 usedin the fixture 10 may be readily removed after cutting to size by asimple vacuum tool, such as a pick and place TEFLON® nose vacuum tool.

The preferred tape 30 for use in the present invention is “TEMP-R-TAPE”of Kapton, the Kapton family “K 100”, “K102”, “K 103”, “K104”, “K 250”,“K 250X” and “K 350” as sold by CHR Industries, Inc. of New Haven, Conn.Such preferred type tape has an adhesive thickness which varies from0.0015 inches to 0.0045 inches, a backing thickness of 0.0005 inches to0.002 inches, and maximum adhesive working temperature range from 150degrees Centigrade to 180 degrees Centigrade.

Referring to drawing FIG. 3, the method of the present invention isshown. As previously stated and shown, a bare die 2 is attached to atest and burn-in fixture 10 by a high temperature pressure sensitiveadhesive tape 30. The electrical connections between the die 2 and thefixture 10 are made by solftool bonding, as shown in drawing FIGS. 1 and2, or may be made by bump contact method, if desired. The adhesive tape30 holds the die 2 securely during all processing of the die 2 untilsuch time as it is desired to remove the die 2 from the fixture 10.After the desired processing, the die 2 is removed from the carrier bysubjecting the carrier to a thermal profile which degrades the adhesiveon the tape 30 to a point where the die 2 can be picked out of thecarrier with minimal force. At that time, any remaining adhesive on thefixture 10 may be removed by heating the fixture 10 until the remainingadhesive is ashed and can be removed from the fixture by any suitabledesired method, such as by a blast of compressed air, or the like, bychemical solvent cleaning, or by mechanical cleaning.

As shown, in the step 100 of the method of the present invention, atest/burn-in fixture 10 suitable for use with the die 2 to be tested isprovided. A cutting die is used to cut the desired piece of hightemperature, pressure sensitive tape 30 to size to fit into thetest/burn-in fixture 10 as step 200. The cut piece of tape 30 istransferred in step 300 to the test/burn-in fixture 10 by any suitablemeans, such as through the use of TEFLON® nose, pick and place toolwhich uses a vacuum to pick up the cut piece of tape 30 and place it inthe fixture 10. The die 2 is mounted on the adhesive coating of the tape30 in the test/burn-in fixture 10 as step 400 of the present invention.At this time the bond pads 22 on the die 2 are connected to the contactpads 20 of the fixture 10 by suitable means as step 500 of the presentinvention. At step 600,of the present invention, the die 2 is tested andburned-in as desired in the fixture 10 in which the die 2 is retainedthrough the use of suitable adhesive tape 30. After testing and burn-inof the die 2, as step 700 of the present invention, the die 2 andfixture 10 are heated to a sufficient temperature to degrade theadhesive holding the die 2 on the tape 30 to allow the removal of thedie 2 from the tape 30. As step 800 of the present invention, the die 2is removed from the fixture 10 after sufficient heating thereof todegrade the adhesive on the tape 30. Subsequent to the removal of thedie 2 from the fixture 10, as step 900 of the present invention, thetape 30 is removed from the fixture 10 and is disposed in a suitablemanner. At this time the fixture 10 is cleaned, as step 1000 of thepresent invention, to remove any remaining adhesive from the fixture 10to allow the reuse thereof. The preferred method of cleaning anyremaining adhesive from the fixture 10 is to heat the fixture 10 to asufficient temperature to ash any remaining adhesive. Such a suitabletemperature for the preferred tape and adhesives as described herein isin the range of 260 to 300 degrees Centigrade to degrade the adhesive toallow the removal of the die 2 from the fixture 10 and ash any remainingadhesive of the fixture 10. At this time the fixture 10 may be easilycleaned by any suitable method of any ash adhesive thereon for reuse.

Referring to drawing FIG. 4, tape 30 is shown having a suitable backing32, such as paper, being supported on a cutting surface 34. A cuttingdie 36 of the desired configuration is used to cut the tape to be usedin the fixture 10 to retain the die 2 therein during testing andburn-in. The cutting die 36 may be actuated by any suitable apparatus ormay comprise a cutting wheel, if desired. After cutting the tape 30 tothe desired configuration, a vacuum pick and place tool 38 having aTEFLON® nose 40 is used to transfer the piece of tape 30 to the fixture10. The vacuum pick and place tool maybe of any suitable design andactuation for use in placing the piece of tape 30 in the fixture 10.

From the foregoing it can be seen that many changes, additions,deletions, etc. may be made to the present invention which fall withinthe scope thereof such that different types of tape having differingtypes of adhesives may be used. Different types of cleaning of thefixture 10 may be used to remove any adhesive remaining thereon. Thetape 30 may be placed in the fixture 10 by various suitable means, otherthan using a vacuum, to transfer the tape 30. The fixture 10 may be ofany suitable type to retain the die 2 during testing and burn-in. Thedie 2 may be connected to the fixture 10 by any suitable means such aswire bonding or tape automated bonding.

What is claimed is:
 1. A method of retaining a semiconductor die in afixture to perform operations on said semiconductor die, said methodcomprising: providing said fixture; providing tape having adhesive on atleast one side thereof; cutting a piece of the tape having a size to fitin said fixture; transferring the piece of the tape to said fixture;placing said semiconductor die on the piece of the tape transferred tosaid fixture; adhesively securing one of said fixture and saidsemiconductor die by the adhesive on at least one side of the piece ofthe tape: performing operations on said semiconductor die when mountedin said fixture; removing said semiconductor die from said fixture afterperforming said operations on said semiconductor die; and removing thepiece of the tape from the fixture after the performing of saidoperations on said semiconductor die in said fixture.
 2. The method ofclaim 1 further comprising the step of: cleaning said fixture after theremoval of said semiconductor die and piece of the tape therefrom. 3.The method of claim 1 further comprising the steps of: providing saidfixture having at least one contact pad thereon, and providing saidsemiconductor die having at least one bond pad thereon.
 4. The method ofclaim 3 further comprising the step of: connecting the at least one bondpad on said semiconductor die with the at least one contact pad on saidfixture.
 5. The method of claim 4 further comprising the step of: wirebonding the at least one bond pad on said semiconductor die to the atleast one contact pad of said fixture.
 6. The method of claim 4 furthercomprising the step of: tape automated bonding the bond at least one padof said semiconductor die to the at least one contact pad of saidfixture.
 7. The method of claim 1 further comprising the step of:heating said semiconductor die and said fixture to allow removal of saidsemiconductor die from said fixture.
 8. The method of claim 1 furthercomprising the step of: heating said fixture to ash any adhesive thereonafter the removal of said semiconductor die therefrom.
 9. The method ofclaim 1 further comprising the step of: cleaning said fixturemechanically after the removal of said semiconductor die therefrom. 10.The method of claim 1, wherein the piece of the tape is transferred tosaid fixture using a vacuum pick and place tool.
 11. The method of claim10, wherein the vacuum pick and place tool includes a tip.
 12. Themethod of claim 1, wherein the piece of the tape is cut by a die cuttingtool.
 13. The method of claim 1, wherein the tape is coated withadhesive on both sides thereof.
 14. The method of claim 1, wherein thetape includes a paper backing portion.
 15. The method of claim 1 furthercomprising the step of: heating said fixture prior to the removal ofsaid semiconductor die therefrom.
 16. The method of claim 1 furthercomprising the steps of: heating said fixture to a first temperaturebefore the removal of said semiconductor die therefrom; and heating saidfixture to a second temperature after the removal of said semiconductordie therefrom.
 17. The method of claim 15, wherein said fixture isheated to substantially 150 degrees Centigrade before the removal ofsaid semiconductor die from said fixture.
 18. The method of claim 15,wherein said fixture is heated to substantially 180 degrees Centigradebefore the removal of said semiconductor die from said fixture.
 19. Themethod of claim 15, wherein said fixture is heated to substantially 260degrees Centigrade before the removal of said semiconductor die fromsaid fixture.
 20. The method of claim 15, wherein said fixture is heatedto substantially 300 degrees Centigrade before the removal of saidsemiconductor die from said fixture.
 21. The method of claim 1, whereinthe piece of the tape has a thickness substantially in the range of0.0015 inches to 0.0045 inches.
 22. The method of claim 1, wherein thepiece of the tape has an adhesive coating thickness thereon insubstantially the range of 0.0005 inches to 0.002 inches.
 23. The methodof claim 1, wherein the adhesive on the piece of the tape has atemperature range of substantially 150 degrees Centigrade to 189 degreesCentigrade.
 24. A method of retaining a semiconductor die in a fixtureto perform testing and burn-in operations on said semiconductor die,said method comprising: providing said fixture; providing tape havingadhesive on at least one side thereof; cutting a piece of the tapehaving a size to fit in said fixture; transferring the piece of the tapeto said fixture; placing said semiconductor die on the piece of the tapetransferred to said fixture; adhesively securing one of said fixture andsaid semiconductor die by the adhesive on at least one side of the pieceof the tape; performing said testing and burn-in operations on saidsemiconductor die when mounted in said fixture; removing saidsemiconductor die from said fixture after the performing of said testingand burn-in operations on said semiconductor die; and removing the pieceof the tape from the fixture after the performing of said testing andburn-in operations on said semiconductor die in said fixture.
 25. Themethod of claim 24 further comprising the step of: cleaning said fixtureafter the removal of said semiconductor die and the piece of the tapetherefrom.
 26. The method of claim 24 further comprising the steps of:providing said fixture having at least one contact pad thereon, andproviding said semiconductor die having at least one bond pad thereon.27. The method of claim 26 further comprising the step of: connectingthe at least one bond pad on said semiconductor die with the at leastone contact pad on said fixture.
 28. The method of claim 27 furthercomprising the step of: wire bonding the at least one bond pad on saidsemiconductor die to the at least one contact pad of said fixture. 29.The method of claim 27 further comprising the step of: tape automatedbonding the at least one bond pad of said semiconductor die to the atleast one contact pad of said fixture.
 30. The method of claim 24further comprising the step of: heating said semiconductor die and saidfixture to allow removal of said semiconductor die from said fixture.31. The method of claim 24 further comprising the step of: heating saidfixture to ash any adhesive thereon after the removal of saidsemiconductor die therefrom.
 32. The method of claim 24 furthercomprising the step of: cleaning said fixture mechanically after theremoval of said semiconductor die therefrom.
 33. The method of claim 24,wherein the piece of the tape is transferred to said fixture using avacuum pick and place tool.
 34. The method of claim 33, wherein thevacuum pick and place tool includes a tip.
 35. The method of claim 24,wherein the piece of the tape is cut by a die cutting tool.
 36. Themethod of claim 24, wherein the tape is coated with adhesive on bothsides thereof.
 37. The method of claim 24, wherein the tape includes apaper backing portion.
 38. The method of claim 24 further comprising thestep of: heating said fixture prior to the removal of said semiconductordie therefrom.
 39. The method of claim 24 further comprising the stepsof: heating said fixture to a first temperature before the removal ofsaid semiconductor die therefrom; and heating said fixture to a secondtemperature after the removal of said semiconductor die therefrom.
 40. Amethod of securing a semiconductor die in a cavity of a fixture forperforming operations on said semiconductor die, said method comprisingthe steps of: cutting a piece of tape having an adhesive coatingthereon; transferring the piece of tape to said cavity of said fixture;and inserting said semiconductor die in said cavity of said fixturewherein the piece of tape retains said semiconductor die in said cavity.41. The method of claim 40, wherein said semiconductor die has a portionthereof in contact with a portion of the adhesive coating on the pieceof tape.
 42. The method of claim 40, wherein said fixture has a portionthereof in contact with a portion of the adhesive coating on the pieceof tape.
 43. The method of claim 40, wherein the piece of tape hasadhesive coating on a portion of each side thereof.
 44. The method ofclaim 43, wherein said semiconductor die has a portion thereof incontact with a portion of the adhesive coating on one side of the pieceof tape and the fixture has a portion thereof in contact with a portionof the adhesive coating on the other side of the piece of tape.
 45. Themethod of claim 40, wherein the adhesive coating on the piece of tape issubstantially a silicone polymer adhesive.
 46. The method of claim 40,wherein the adhesive coating on the piece of tape is substantially anacrylic adhesive.
 47. The method of claim 44, wherein the adhesivecoating is substantially a silicone polymer adhesive.
 48. The method ofclaim 44, wherein the adhesive coating is substantially an acrylicadhesive.
 49. A method of retaining a semiconductor die in a fixture toperform operations on said die, said method comprising: providing saidfixture; providing tape having adhesive on each side thereof; cutting apiece of the tape having a size to fit in said fixture; transferring thepiece of the tape to said fixture; placing said semiconductor die on thepiece of the tape transferred to said fixture; adhesively securing saidfixture and said semiconductor die by the adhesive on each side of thepiece of the tape; performing operations on said semiconductor die whenmounted in said fixture; removing said semiconductor die from saidfixture after performing said operations on said semiconductor die; andremoving the piece of the tape from the fixture after the performing ofsaid operations on said semiconductor die in said fixture.
 50. A methodof retaining a semiconductor die in a fixture to perform testing andburn-in operations on said die, said method comprising: providing saidfixture; providing tape having adhesive on each side thereof; cutting apiece of the tape having a side to fit in said fixture; transferring thepiece of the tape to said fixture; placing said semiconductor die on thepiece of the tape transferred to said fixture; adhesively securing saidfixture and said semiconductor die by the adhesive on each side of thepiece of the tape; performing said testing and burn-in operations onsaid semiconductor die when mounted in said fixture; removing saidsemiconductor die from said fixture after the performing of said testingand burn-in operations on said semiconductor die; and removing the pieceof the tape from the fixture after the performing of said testing andburn-in operations on said semiconductor die in said fixture.
 51. Amethod of securing a semiconductor die in a cavity of a fixture forperforming operations on said semiconductor die, said method comprisingthe steps of: cutting a piece of tape having an adhesive coating on eachside thereof; transferring the piece of tape to said cavity of saidfixture; and inserting said semiconductor die in said cavity wherein thepiece of tape adhesively retains said semiconductor die in said cavityof said fixture.